Previous work has demonstrated that exposure to an hour of bright light in the morning and the evening during the Polar winter has beneficial effects on circadian phase. This study investigated the effect of a single hour of bright white morning light on circadian phase, sleep, alertness and cognitive performance. Nine individuals (eight male, one female, median age 30 years), wintering at Halley Research Station (75°S), Antarctica from 7th May until 6th August 2007, were exposed to bright white light for a fortnight from 08:30 to 09:30 h, with two fortnight control periods on either side. This sequence was performed twice, before and following Midwinter. Light exposure, sleep and alertness were assessed daily by actigraphy, sleep diaries and subjective visual analogue scales. Circadian phase (assessed by urinary 6-sulphatoxymelatonin rhythm) and cognitive performance were evaluated at the end of each fortnight. During light exposure circadian phase was advanced from 4.97 ± 0.96 decimal hours (dh) (mean ± SD) to 4.08 ± 0.68 dh (p = 0.003). Wake-up time was shifted by a similar margin from 8.45 ± 1.83 dh to 7.59 ± 0.78 dh (p < 0.001). Sleep start time was also advanced (p = 0.047) but by a lesser amount, consequently, actual sleep time was slightly reduced. There was no change in objective or subjective measures of sleep quality or subjective measures of alertness. An improvement in cognitive performance was found with both the Single Letter Cancellation Test (p < 0.001) and the Digit Symbol Substitution Test (p = 0.026) with preserved circadian variation. These beneficial effects of a single short duration light treatment may have implications not only for the Antarctic but other remote environments where access to natural light and delayed circadian phase, is problematic. These results require validation in larger studies at varying locations.
This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 12 February 2023.
All research outputs
#21,791,646
of 34,557,610 outputs
Outputs from Neuroscience Letters
#6,430
of 9,650 outputs
Outputs of similar age
#142,575
of 213,143 outputs
Outputs of similar age from Neuroscience Letters
#28
of 57 outputs
Altmetric has tracked 34,557,610 research outputs across all sources so far. This one is in the 36th percentile – i.e., 36% of other outputs scored the same or lower than it.
So far Altmetric has tracked 9,650 research outputs from this source. They typically receive a little more attention than average, with a mean Attention Score of 5.4. This one is in the 32nd percentile – i.e., 32% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 213,143 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 32nd percentile – i.e., 32% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 57 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 50% of its contemporaries.
